JPH08216441A - Device and method for color heat-sensitive recording - Google Patents

Abstract

PURPOSE: To provide a color heat-sensitive recording device for tone controlling without affecting dots by the situation of application energy to the peripheral dots. CONSTITUTION: In a color heat-sensitive recording device, at least three heat- sensitive coloring layers of different colors and heat recording sensitivity are formed on a substrate, and at least two of the three layers are used for recording on a color heat-sensitive recording material provided with photofixing properties generated by yellow magenta waves respectively in proper wave range by using a thermal head. Applied pulses of dots are controlled continuously or discontinuously by referring a value, to be converted from a tone data in a tone control section 14 for converting the tone data to be recorded to power driving pulses for a thermal head heating resistor 9 in compliance with the tone data value, to a look-up table 16, and in the case of discontinuous control, the on/off ratio is controlled to make the temperature of the heating resistor 9 of the thermal head not affected by the application of energy to the peripheral dots.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention has at least three thermosensitive coloring layers on a support, each of which has a different coloring color and a different thermal recording sensitivity, and at least two of the thermosensitive coloring layers have a wavelength range peculiar to each. Color thermal recording apparatus and method for recording a color image by using a color thermal recording material having optical fixing property by electromagnetic waves and using a thermal head in which a plurality of heating elements are arranged in a line in the main scanning direction of the color image Regarding

[0002]

2. Description of the Related Art Generally, a color thermosensitive recording material of this type has a thermosensitive coloring layer of three layers of cyan, magenta and yellow formed on a support, and the thermosensitivity of each thermosensitive layer is different from that of cyan, magenta and yellow. The thermal recording sensitivity is high in this order. The cyan thermosensitive layer having the lowest sensitivity is higher than the sublimation type thermal transfer temperature, and the magenta thermosensitive layer generally corresponds to the sublimation type thermal transfer temperature. Furthermore, since a chemical reaction between a coupler and a diazonium compound or an electron-donating dye precursor and an electron-accepting compound is generally used for color development, a certain amount of energy necessary for the chemical reaction to occur is longer than that of the sublimation type. I have to give it time. The heat-sensitive recording method and the sublimation-type thermal transfer recording method are suitable for recording a halftone image such as a photograph because the gradation of density changes according to the amount of heat applied.

Printing in color thermal recording has a high thermal recording sensitivity in the order of cyan, magenta, and yellow, so that the voltage supplied to the thermal head is switched for each color. As a method of expressing the gradation within one dot, the number of pulses having different widths is controlled as shown in FIG. 2 (hereinafter referred to as method A).
Or, the number of applied pulses for one dot is one, but a method of controlling the pulse width (hereinafter referred to as method B)
Has been taken. However, the degree of color development of the dots is slightly different due to the heat accumulation of the thermal head due to the printing of adjacent or neighboring dots, and accurate gradation expression cannot be performed. Applied pulse (hereinafter, referred to as correction method C), the number of applied pulses in one dot in the method A, and the pulse width in one dot in the method B depending on the situation of energy application to the peripheral dots. The effect of printing adjacent or peripheral dots is reduced by adding a control for changing the value (hereinafter referred to as correction method D).

[0004]

FIG. 3 is a diagram showing the temperature rise of the heating resistor in the magenta layer printing of the color thermosensitive recording material when an applied pulse is applied to the heating resistor of the thermal head, which corresponds to adjacent dots. 7 is a temperature curve of the heating resistor when the energy is applied to the heating resistor. In FIG. 3, the application time is 18 mS and the non-application time is 2 m
S has a line cycle of 20 mS, and the thermal head supply voltage is 12V. The temperature of the heating resistor 9 of the thermal head shown in FIG. 1 rises according to the application time and reaches the color development temperature at 110 ° C. From FIG. 3, the temperature of the heating resistor 9 rapidly rises for 5 to 10 mS according to the experiment of the writer for a certain time after the applied pulse is applied to the heating resistor (hereinafter, this state is referred to as an excessive state), When energized for a longer time, the temperature does not rise sharply and becomes almost constant (hereinafter this state is called the saturated state). In FIG. 3, the lower limit of the transient region temperature is 70 ° C. and the upper limit of the saturated region temperature is 130 ° C.
Is. The strobe signal has a voltage of 5V.

As shown in FIG. 4, the difference greatly depends on whether or not the heating resistors 9 in the dots adjacent to each other in the main scanning direction are energized. FIG. 4 is a heating temperature curve of a heating resistor in cyan layer printing, in which the thermal head supply voltage is 15V, the strobe signal voltage is 5V,
It is a figure in application time 18mS and non-application time 2mS. According to an experiment by the writer, for example, when a 300-dot-per-inch (dpi) thermal head is used, up to two dots on the left and right with respect to the main scanning direction are affected, and a dot further away is affected. The impact can be ignored. However, in the case of the sublimation type, since the dye applied to the ink sheet is only sublimated, in general, the control can be performed within the time of 3 to 10 mS, that is, only the transient state in which the saturated state does not occur. It is less affected and can be corrected by the correction method D to some extent.

However, in the case of color thermosensitive recording utilizing the chemical reaction of a diazonium compound and a coupler, it takes 10 to 20 mS since the color development requires a certain time or more at a temperature higher than the temperature necessary for each color forming layer to undergo a chemical change. The above application is required, and the saturation temperature region greatly contributes to color development. It is also conceivable to increase the supply voltage to the thermal head to shorten the printing time, that is, to apply the same energy in a shorter time, but this method supports each color forming layer of the color thermosensitive recording material. It is not preferable because it destroys the support and the protective layer of the heat-sensitive recording material. Therefore, the color thermal recording is much more affected by the adjacent dots than in the sublimation type. For example, in the case of 255 gradation control, even if the gradation of the dot is 255, the gradation of the adjacent dot is 0. That is, when the adjacent dots are not energized, as shown in FIG. 4, the saturation temperature of the dot does not become higher than the coloring temperature and the coloring of the dot may be the same as the gradation 0.

In order to prevent this, energy is also applied to the heating resistors corresponding to the adjacent dots to the extent that the adjacent dots do not develop color. Specifically, the strobe signal voltage is 5 V, the application time is 11 mS, and the non-application time is 9 mS. Fig. 5 shows the temperature rise of the dot when applied by applying the temperature curve. The temperature curve rises when the adjacent dots are energized, but when it is not energized, the temperature curve is lower than when energized and the energy applied to the color thermosensitive recording material is decreased. Is significantly different, and it is difficult to control the gradation in consideration of this. Further, the energy is such that the dot at the same position on the previous line with respect to the dot is not colored, that is, the voltage of the strobe signal is 5 V and the application time is
Even if the voltage is applied at a cycle of mS and a non-application time of 9 mS, the temperature of the heating resistor decreases to about 40 ° C. before printing of the dot as shown in FIG. It only promotes color development. Therefore, the conventional gradation control method has a problem that it is difficult to accurately express gradation in the case of color thermal recording.

Therefore, an object of the present invention is to solve the above-mentioned conventional problems so that the saturation temperature of the heating resistor in the dot of the thermal head is not affected by the energization state of the heating resistor in the surrounding dots. That is, it is to obtain a color thermosensitive recording apparatus and method capable of performing gradation control so that the dot is not affected by the state of energy application in the peripheral dot.

[0009]

In order to solve the above-mentioned problems, in the invention described in claim 2, while the pulse is applied to the dot, the pulse of the dot adjacent to the main scanning direction is applied. For example, if the applied pulse of the dot is made discontinuous during that period and the pulse of the dot adjacent to the main scanning direction is not applied, the applied temperature of the dot is made continuous during that period so that the saturation temperature becomes almost equal. This is to reduce the influence of surrounding dots on the dot. Further, in the invention described in claim 3, when the applied pulse of the corresponding dot is discontinuous, if the total amount after weighting each state whether the pulse is applied to the peripheral dots in the main scanning direction is large, If the total amount after weighting each state of whether or not a pulse is applied to the peripheral dots in the main scanning direction is small by increasing the off time of the applied pulse of that dot, the application pulse of that dot during that period is turned off. By shortening the time, the saturation temperature is kept almost the same, and the influence of surrounding dots on the dot is eliminated.

According to the invention described in claim 4, when the applied pulse of the dot is discontinuous, the saturation temperature is kept substantially equal by controlling the number of discontinuous pulses in one dot, and the peripheral dots are applied to the dot. The effect of is reduced. Further, in the invention described in claim 5, in the inventions of claim 2, claim 3, and claim 4, the temperature at the start of pulse application of the dot is low depending on the situation of energy application in the preceding line or the preceding line. In this case, the saturation temperature is kept approximately equal by applying pulses continuously or discontinuously so that they do not overlap with the applied pulses in the previous line after the start of pulse application, and the influence of surrounding dots on the dots is reduced. It was done.

Further, as a precondition for the inventions of claims 2 to 5, in the invention of claim 1, the gradation data of the dot and peripheral dots are converted into strobe signals for controlling the energization of the heating resistors of the dots. A look-up table (LUT) for strobe signal data corresponding to the gradation data of the dot and peripheral dots in the gradation control unit.
The effect of peripheral dots on the dot is reduced.

[0012]

In the color thermal recording apparatus constructed as described above, the saturation temperature can be easily kept the same regardless of the energy application state of the peripheral dots, so that accurate gradation expression can be achieved. .

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 7 schematically shows the constitution of the color thermosensitive recording material used in the present invention. The color thermosensitive recording material has a cyan thermosensitive coloring layer, a magenta thermosensitive coloring layer, a yellow thermosensitive coloring layer, and a protective layer which are sequentially formed on a support. The thermal recording sensitivities of the respective layers are different, and the sensitivities increase in the order of cyan, magenta, and yellow. Regarding the concentration of each layer, the higher the temperature in each temperature zone, the higher the concentration. Further, the yellow layer has a light fixing property by an electromagnetic wave in the vicinity of 420 nm, and the magenta layer has a light fixing property by an electromagnetic wave in the vicinity of 365 nm.

FIG. 8 shows a schematic structure of a color thermosensitive recording apparatus according to this embodiment. A heating element 2-1 is arranged in the thermal head 2 so as to face the platen roller 3, and the platen roller 3 and a pair of paper feed rollers 5 are sub-scanning direction line by line by a drive motor 7 controlled by a controller (not shown). The color thermosensitive recording material 6 can be conveyed forward and backward. An optical fixing device 4 is provided between the thermal head 2 and the paper feed roller 5, and the optical fixing device 4 has an ultraviolet lamp 4-2 for fixing the magenta layer having an emission peak near 365 nm and an emission peak near 420 nm. And an ultraviolet lamp 4-1 for fixing the yellow layer and a reflector 4-3. The heating element 2-1 corresponds to the heating resistor 9 of FIG.

Next, the operation of this device will be described. The color thermosensitive recording material 6 is sandwiched between the thermal head 2 and the platen roller 3, and the platen roller 3 and the paper feed roller 5 are rotated in the sub-scanning direction line by line by the drive motor 7 so that the color thermosensitive recording material 6 is corrected. First, the yellow layer is thermally recorded between the heating element 2-1 of the thermal head and the platen roller 3 while being conveyed in the direction. After thermal recording of the yellow layer is completed, the color thermosensitive recording material 6 is conveyed to the optical fixing section. The optical fixing device 4 irradiates the color thermosensitive recording material 6 with ultraviolet rays by causing the yellow layer fixing ultraviolet lamp 4-1 having an emission peak in the vicinity of 420 nm to emit light, thereby optically fixing the yellow layer. As a result, even if heat after the yellow layer color development sensitivity is applied to the color thermosensitive recording material 6, the yellow layer will not develop color. After the optical fixing of the yellow layer is completed, the paper feed roller 5 and the platen roller 3 are rotated in the opposite direction, and the print start line portion of the color thermosensitive recording material 6 is returned to the position of the heating element 2-1 of the thermal head 2.

Next, the supply voltage to the thermal head 2 is set to 14
V and 3 V higher than in the case of yellow layer printing, and then the paper feed roller 5 and the platen 3 are rotated in the forward direction to carry out thermal recording of the magenta layer while conveying the color thermosensitive recording material 6. After the thermal recording of the magenta layer is completed, the color thermosensitive recording material 6 is conveyed to the optical fixing section. Optical fuser 4 is 365n
The color thermosensitive recording material 6 is irradiated with ultraviolet rays by causing the magenta layer fixing ultraviolet lamp 4-2 having an emission peak near m to emit light, whereby the magenta layer is optically fixed. After that, even if heat exceeding the color development sensitivity of the magenta layer is applied to the color thermosensitive recording material, the magenta layer does not develop color. After the optical fixing of the magenta layer is completed, the paper feed roller 5 and the platen 3 are rotated in the opposite direction, and the print start line portion of the color thermosensitive recording material 6 is returned to the position of the heating element 2-1 of the thermal head 2.

Next, the supply voltage to the thermal head is 17V.
Then, the cyan layer is heat-recorded while the color heat-sensitive recording material 6 is conveyed by rotating the paper feed roller 5 and the platen 3 in the normal direction after making the height higher than in the case of the magenta layer printing. After the cyan layer is thermally recorded, the color thermosensitive recording material 6 is discharged from the apparatus through a paper discharge port (not shown).

FIG. 1 shows an embodiment of the thermal head drive section of the present invention. Digital image signal is frame memory 1
5, the data for one line for each color line is called by the gradation control unit 14. Then 1 for each gradation
The serial drive data for one line is converted, and the serial drive data for one line is sent to the shift register 13 by a clock signal, converted into a parallel signal, and then latched by a latch signal. AND gate 1
1 outputs Hi when the signal latched from the latch 2 to the AND gate 11 is Hi when the strobe signal is input from the gradation control unit 14, and the transistor 10 is connected to each output terminal. When the output of the AND gate 11 is Hi, it is turned on and each heating resistor 9 of the thermal head is energized. Here, Hi is 5V and L
ow means 0 V, and the same applies to those described below. The gradation control unit 14 and the look-up table 16 are arranged so that they can communicate with each other.

When this strobe signal is applied, the look-up table 16 stored in the memory or the like stores the latch signal for two dots on the left and right with respect to the heating resistor 9 of the dot in the main scanning direction depending on whether it is Hi or Low. Whether the applied pulse in the gradation is continuous or discontinuous,
And read the information of the on / off ratio when discontinuous,
The strobe signal is applied accordingly. The lookup table 16 is stored in a storage device such as a memory device, and an example is shown in FIG. As a result, for example, the strobe signal and the temperature change in the magenta layer printing of the heating resistor 9 of the dot when the two dots on both sides of the dot are energized are as shown in FIG. The temperature is 70 ° C., the color development temperature is about 110 ° C., and the upper limit of the saturation region is about 130 ° C. In this case, application time 18
Strobe signal becomes discontinuous in all of mS,
The on / off ratio is approximately 1: 1 and the number of pulses is 640. The individual pulse widths are not the same, but details are omitted. The non-application time is 2 mS and the line cycle is 20
mS, and the voltage of the strobe signal is 5V.

The heating resistor 9 of the right two dots is not energized,
FIG. 10 shows the strobe signal and the temperature change in the magenta layer printing of the dot when only the heating resistor 9 of the two dots on the opposite side is energized, and the lower limit value of the transient region is about 70 ° C. , The strobe signal becomes discontinuous during the entire application time of 18 mS, the on / off ratio is approximately 3: 1 and the number of pulses is 640. The individual pulse widths are not the same, but details are omitted. The non-application time is 2 mS, the line period is 20 mS, and the voltage of the strobe signal is 5V.

Heat generating resistors 9 of two dots on the left and right of the dot
FIG. 1 shows the strobe signal and the temperature change in the magenta layer printing of the heating resistor 9 of the dot when the dot is not energized.
1, the lower limit of the transient region is about 70 ° C., and in this case, the strobe signal is continuous during the entire application time of 18 mS. The non-application time is 2 mS and the line period is 2
It is 0 mS, and the voltage of the strobe signal is 5V.

Further, when the dots are full gradation and the left and right two dots are all half gradation, the temperature change in the magenta layer printing is as shown in FIG. 12, and the transient region lower limit value is about 7
At 0 ° C., in this case, the strobe signal is applied for 18 mS, discontinuous for 10 mS from the start of application, and continuously for 8 mS after that. The ON / OFF ratio during discontinuity is about 1: 1 and the number of pulses is 420. is there. The individual pulse widths are not the same, but details are omitted. Non-application time is 2m
S, the line period is 20 mS, and the voltage of the strobe signal is 5V.

Although FIGS. 9, 10 and 12 do not have a smooth temperature curve as shown in FIG. 11, since the resolution in a general color printer is 150 to 600 dpi, it can be said that the degree of color appearance is almost the same. .
In the above-described embodiment, the coloring is controlled by making the applied pulse continuous or discontinuous, or by controlling the on / off ratio when the pulse is discontinuous, but when it is discontinuous, it is divided. It may be controlled by changing the number of pulses, or the amount of energy applied to the previous line or earlier lines may be small, which may slow down the temperature rise of the dot and increase the time to reach the saturation region. In order to prevent this, a strobe signal with a line cycle of 20 mS is applied for 11.5 mS and not applied for 3.5 m before the start of application of the application pulse for the dot, as shown in the pulse of FIG. 13, for example.
S, application time is 3 mS, non-application time is 2 mS, and application pulse may be applied with an applied voltage of 5 V to control continuously or discontinuously.

[0024]

As described above, according to the present invention, the gradation control is performed so that the saturation temperature of the heating resistor is not influenced depending on the energy application state of the peripheral dots, and therefore the energy application state of the peripheral dots is controlled. The effect is that accurate gradation expression can be achieved regardless of the relationship.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration and a driving method of a thermal head driving section in an embodiment of a color thermal recording apparatus according to the present invention.

FIG. 2 is a waveform diagram showing each signal of a thermal head drive unit in a conventional gradation control method.

FIG. 3 is a diagram showing a strobe signal and a temperature curve of a heating resistor of a thermal head with respect to the strobe signal for explaining a color thermal recording method of a conventional example.

FIG. 4 is a diagram showing a strobe signal and a temperature curve of a heating resistor of a thermal head with respect to the strobe signal for explaining a color thermosensitive recording method of a conventional example.

FIG. 5 is a diagram showing a strobe signal and a temperature curve of a heating resistor of a thermal head with respect to the strobe signal for explaining a color thermosensitive recording method of a conventional example.

FIG. 6 is a diagram showing a strobe signal and a temperature curve of a heating resistor of a thermal head with respect to the strobe signal for explaining a color thermosensitive recording method of a conventional example.

FIG. 7 is an explanatory diagram showing an example of a layer structure of a color thermosensitive recording material.

FIG. 8 is a schematic view of a color thermal recording apparatus embodying the present invention.

FIG. 9 is a diagram showing a strobe signal and a temperature curve of a heating resistor of a thermal head corresponding to the strobe signal for explaining the color thermosensitive recording method of the present invention.

FIG. 10 is a diagram showing a strobe signal and a temperature curve of a heating resistor of a thermal head with respect to the strobe signal for explaining the color thermosensitive recording method of the present invention.

FIG. 11 is a diagram showing a strobe signal and a temperature curve of a heating resistor of a thermal head with respect to the strobe signal for explaining the color thermosensitive recording method of the present invention.

FIG. 12 is a diagram showing a strobe signal and a temperature curve of a heating resistor of a thermal head with respect to the strobe signal for explaining the color thermal recording method of the present invention.

FIG. 13 is a diagram showing a strobe signal and a temperature curve of a heating resistor of a thermal head with respect to the strobe signal for explaining the color thermosensitive recording method of the present invention.

FIG. 14 is a schematic diagram showing an example of the configuration of a look-up table of the color thermal recording apparatus embodying the present invention.

[Explanation of symbols]

 1 Thermal Head Voltage Source 2 Thermal Head 3 Platen Roller 4 Optical Fixing Device 5 Paper Feeding Roller 6 Color Thermal Recording Material 7 Drive Motor 8 Motor Driver 9 Heating Resistor 10 Transistor 11 AND Gate 12 Latch 13 Shift Register 14 Gradation Control Unit 15 Frame memory 16 lookup table

Claims (5)

[Claims] 1. At least three thermosensitive coloring layers having different coloring colors and different thermal recording sensitivities are provided on a support, and at least two layers among them have photo-fixing property by electromagnetic wave in a wavelength region unique to each layer. Gradation data to be recorded in a color thermal recording apparatus that records a color image using a thermal recording head equipped with a color thermal recording material equipped with a plurality of heating resistors arranged in a line in the main scanning direction of the color image. A color having a look-up table for referencing a value to be converted from corresponding gradation data in a gradation control unit for converting into a current driving pulse of a thermal head heating resistor according to the value of the gradation data. Thermal recording device. 2. A color thermal recording method for recording a color image using the color thermal recording apparatus according to claim 1, wherein the thermal head is within one dot or one gradation depending on the energy application state of peripheral dots. A color thermosensitive recording method characterized in that the application pulse of is controlled continuously or discontinuously. 3. A color thermal recording method for recording a color image using the color thermal recording apparatus according to claim 1, wherein a pulse applied to a thermal head within one dot or one gradation is discontinuous. A color thermosensitive recording method characterized in that the on / off ratio is controlled according to the energy application state of the peripheral dots. 4. A color thermal recording method for recording a color image using the color thermal recording apparatus according to claim 1, wherein a pulse applied to a thermal head within one dot or one gradation is discontinuous. A color thermosensitive recording method characterized in that the number of pulses is controlled according to the state of energy application to peripheral dots. 5. The invention according to claim 1, claim 2 or claim 3, wherein the application pulse within one dot is continuously applied to the front side from the start of application with respect to time in accordance with the energy application state of the peripheral dots. A color thermosensitive recording method characterized by discontinuous control.